Effect of obstacle on the H2/CO/Air explosion characteristics under lean-fuel conditions

This experimental study focused on effect of obstacle on the syngas (H-2/CO) explosion characteristics under lean fuel conditions. The relationship between the flame propagation characteristics and explosion intensity, and effects of syngas concentration, obstacle number and blocking rate on explosion parameters were obtained. Results indicate that the flame propagation and pressure rise were corresponding inside the closed vessel. Obstacle could affect the flame propagation process by changing flame structure, which further indirectly affected the flame velocity and explosion intensity. The "reverse oscillation " flame appeared in the later stage due to the interaction between the flame front and reflected pressure wave, and affected by the obstacle condition and syngas concentration. Meanwhile, the peaks of velocity history were obviously increased, and their appearance moment and the interval time between adjacent peaks were decreased with increasing syngas concentration, obstacle number and blocking rate. Especially the maximum flame propagation velocity (v(max)) was increased by 88.90%, 60.59% and 61.65%, respectively. The maximum explosion pressure (delta P-max) and two peaks of pressure rising rate history also presented an increasing trend. However, the first peak appearance moment had a slight delay due to the blocking effect with the increases of obstacle number and blocking rate in the initial stage of flame propagation.